Electronic multiplier



Nov. 22, 1960 R. E. BELL ErAL 2,961,160

ELECTRONIC MULTIFLIER Filed May 28, 1956 9 Sheets-Sheet 3 Tl: C224 Y I IN VEN T015' ROBERT E. BELL 2272i g E' BY MAnvARD c. YEAsm/G 9 Sheets-Sheet 4 LM L/ S o u o lml SET Y .NH .Nnhwl Me M TEE R m y m I IU-. W? www# n IMD Sgm .www mm n wwl n m JnfN m QQN A mmm# @WNFR M Y u amm nu B J n vw d l a l l -qwmm l L R. E. BELL I'AL ELECTRONIC MULTIPLIER Nov. 22, 1960 Filed May 28, 1956 Ww W W w WW Wwww,

Nov. 22, 1960 R. E. BELL ErAL 2,961,160

ELECTRONIC MULTIPLIER Filed May 28, 1956 9 Sheets-Sheet 5 97 uw we 340 2 ll- 7323 3/0 326 N307 37 3/5 I6 332 336 33/ jf g f\ gf 5 339- ROBERT E. 5E LL MA Y/VAPD C YEAS TIA/G FL-$7.32! gg ATTORNEYS Nov. 22, 1960 R. E. BELL ETAL ELECTRONIC MULTIPLIER 9 Sheets-Sheet 6 Filed May 28, 1956 ss i no J B+ ghi? i, 432

Lw L/ sw m .A am mrc. mm w m YM B AT T GRA/E YS Nov. 22, 1960 R. E. BELL ErAL ELECTRONIC MULTIPLIER 9 Sheets-Sheet '7 Filed May 28, 1956 INVENTORS ROBE/W' E. BELL MAYNARD C YEAST//VG ATTORNEYS Nov. 22, 1960 R. E. BELL ErAL 2,951,160

ELECTRONIC MULTIPLIER Filed May ze, 195e 9 sheets-sheet s 1N V EN TORS ROBERT E. BEL L MAY/VA RD C. YEAS TING A 7' TORNEYS United States Patent() nLncrRoNIc MULTIPLIER Robert E. Bell, roietlo, and Maynard C. Yeasting, El-

more, hio, assignors, by mesne assignments, to Toledo Scale Corporation, Toledo, Ohio, a corporation of Ohio nnen May 2s, 195s, ser. No. 587,684

s cranes. (ci. 23S-160) This invention relates to computing equipment and in particular to electronic multiplying mechanism that perates entirely on pulse counting methods.

Mechanical methods for multiplication such as the o1'- dinary desk computing and accounting machines are relatively slow in operation. The more complicated types of mechanical multipliers working on the partial product principle are capable of multiplying two, ive or six digit numbers in approximately three seconds. Other types using the successive addition method require considerably longer time to perform a comparable multiplication operation. Electronic computing equipment has been constructed using electronic circuits to achieve extremely rapid or high speed operation in which multi-digit numbers are multiplied in a millsecond or less. These ultra fast or high speed computers are in general extremely expensive and complicated and require the services of highly trained personnel to operate and maintain them.

The electronic multiplier according to this invention is intended to supply or ll the gap between the slow speed mechanical types of multipliers and the extremely high speed electronic multipliers. It has the sfmplicity and direct action of a mechanical multipliers combined with the speed of electronic counters capable of operating in the neighborhood of a hundred thousand counts per second. In order to secure simplicity and freedom frtm highly complex synchronizing problems the improved counter operates on pulse techniques in which pulses representing the various digits of the multiplier and multiplicand are generated and added in successive stages or decades of an electronic counter. By counting pulses in a decimal system rather than performing the mu'tipl'cation by the binary pulse train method it is possible to secure considerable reduction in complexity in the equipment as well as increased reliability in operation.

The principal object of this invention is to provide a simple, electronic multiplying circuit and apparatus that is relatively simple to construct, reliable in operaton, and fast enough for all ordinary commercial applications.

Another object of the invention is to provide improved pulse generating equipment that can reliably produce selected numbers of pulses at various repetition rates sultable for counting in electronic counters.

A still further object of the invention is to provide improved switching mechanism for transmitting the pulses generated in the pulse generators to the respective decades of a multi-decade electronic counter to effect column shift of the input to the counter.

A still further object of the invention is to provide a simple electro-mechanical switching device and circuit for successively switching the outputs of the pulse generators to various decades of the electronic counter to perform the column shift operation utilized in most multiplying operations.

More specic objects and advantages will be apparent from the following description of preferred forms of the invention.

ice

According to the invention the improved electronic multiplier comprises lirst generating means for generating a series of pulses representing a multiplier, a multiplicand pulse generator that is repetitively triggered -by the pulses from the rst pulse generating means, at least one output circuit from the multiplicand pulse generator, switching means settabie according to the value of the multiplicand connected to the multiplicand generator to regulate the number of pulses appearing on the output circuit for each rst generating means pulse, and an electronic counter for counting the pulses appearing on said output circuit.

Preferred forms of the invention are illustrated in the accompanying drawings.

In the drawings:

Figure I is a block diagram illustrating the general organization of the multiplier including the switching that is necessary for the introduction of the multiplier and multiplicand factors.

' Figure II is a block diagram illustrating a form of the invention in which a stepping relay is employed to provide a column shift operation for repetitive use of the multiplier and multiplicand generators as multiplication by each digit of the multiplier is completed. Y

Figure III is a schematic diagram of a circuit for operating the stepping relay shown in Figure Il. Y r

Figure IV is a schematic diagram of a portion of one of the pulse generators illustrated or used in the circuits shown in Figures Il and II.

Figure V is a schematic diagram of another of the pulse generators and signal combining matrix that is used in the multiplier systems illustrated in Figures I and II.

Figure VI is a schematic diagram illustratingA the carry pulse storage system and amplier that is employed between successive decades of the electronic counter. l

Figure VII is a schematic diagram of one stage of a multi-stage electronic counter suitable for use in the system.

Figure VIII is a schematic diagram of another type of pulse generator suitable for use in the system.

Figure VIIIa is a diagram of the wave forms obtained in the circuit shown in Figure VlII.

Figure IX is a schematic diagram of a portion of an; other type of pulse generator suitable for use in the system.

Figure X shows another form of pulse generator that may be used and substituted for those illustrated in Figures I and II.

Figure XI is a schematic diagram of an electronic sequencing control for operating the computer shown in Figure II.

Figure XII is a schematic diagram of a suitable form of electronic switching or gating circuit for use with the sequencing control circuit.

Figure XIII is a block diagram of another circuit suitable for multiplying by the pulse counting technique.

These specific gures and the accompanying description are intended merely to illustrate the invention and not impose limitations on the claims.

In the circuit illustrated in Figure I, a start pulse which may be a positive spike of voltage is supplied through an input line 1 and a selector switch 2 into any of ten leads associated with a rst or units pulse generator 3. The pulse generator 3 comprises a plurality of single cycle oscillators arranged in series or cascade connection such that the pulse from the input lead 1 triggers a selected one of the oscillators which in turn triggers its neighbor and so on to the end of the series. As each of these oscillators triggers it provides a pulse on a units output lead 4 and as the last oscillator of the chain or series executes its cycle of oscillation it produces a pulse on a second or terminal pulse output lead 5. The lead 5 is connected to a selector switch 6 associated with a second pulse generator 7 for the tens digit of the multiplier. The selected number of tens pulses are delivered through an output lead 8 and a terminal pulse through a lead 9 that is connected through a selector switch 10 to a third pulse generator 11 representing the hundreds digit of the multiplier.

The hundreds pulse 4generator 11 is similar to the others and delivers the selected number of pulses over its output lead 12 and its terminal pulse over its output lead 13.l The terminal pulse on lead 13 is transmitted through a selector switch 14 associated with a fourth pulse generator 15 representing the thousands digit of the multiplier. The thousands pulse generator 15 is similar to the others and delivers its selected number of pulses over its output lead 16 and if there `are more places in the multiplier it delivers a terminal output pulse through a lead 17 which would be connected to the next pulse generator in the series. y

- The lpulse generators 3, 7, 11, and 15 constitute means for generating series of pulses representing the various digits of a multiplier. While the system has been shown to operate on a decimal arrangement it is possible and in some cases preferable to generate all of the multiplier pulses in a single pulse generator as a continuous series proportional in number to the factor. This is particularly true where the multiplier is a factor representing the reading of a condition responsive instrument, for example a weighing scale, and in which the factor is obtained by scanning or otherwise interpreting a graduated chart. Likewise, while the system is shown as a decimal arrangement other units yalso can be used such as a duodecimal or octal system by merely changing the number of impulses to be generated as the pulse is transmitted through each oscillator chain.

The output pulses from the units pulse generator 3 delivered through the output lead 4 are applied to a multiplicand pulse generator 20 that comprises a plurality of single cycle oscillators arranged in groups and each executing a complete cycle of operation for each input pulse received on the lead 4. The groups of oscillators in the generator 20 are arranged such that a first output lead 21 delivers two pulses for each input pulse, a second output -lead 22 delivers four pulses for each input pulse while a third output lead 23 delivers two pulses foreach input pulse and a fourth output lead 24 delivers a single output pulse for each input pulse. In addition four pulses are generated and delivered one through each of output leads 25, 26, 27, and 28 which are connected through a cable 29 to effect clearing of certain carry storage circuits of an electronic counter arranged to indicate the product or result of the computation. The pulses delivered on the output leads 21 to 28 inclusive are sequential in time in that the pulses on the lead 21 are the iirst two pulses to. be generated following the receipt of a pulse over the lead 4, the next four pulses to be generated appear on the lead 22, the next two on the lead 23, the next one on the lead 24, and the following four pulses on the leads to 28 inclusive. As a matter of expediency the pulse on the leads 24 to 25 may be the same pulse since the counter Vuses the leading edge of the voltage pulse while the carry storage circuit uses the trailing edge.

The Ipulses appearing on the leads 21 to 24 inclusive are fed through a diode matrix combining circuit 30 which has nine output leads 31 carried in a cable 32 and arranged to supply nine terminals of each of a set of selector switches 33, 34, 35, and 36. The selector switches correspond to the thousands, hundreds, tens `and units places of a multiplicand. The output leads 31 from the diode matrix 30 receive, through the switching diodes from the leads 21 to 24, a number `of pulses corresponding to their Vplace in the series. Thus the tirst of the leads 31 carries a single pulse per input pulseon the lead 4 while Y r the'last-of the leads 31 carries nine pulsesper input pulse.

By properly setting the selector switches 33 to 36 according to the digits of themultiplicand, corresponding numbers of pulses are fed to the output leads of the various selector switches. Thus as shown the units switch 36 is connected to the fifth point of the switch 36 so as to deliver five pulses through its output lead 37 for each pulse received over the lead 4 into the generator 20. These pulses on the lead 37 are fed through an amplifier 38 into a units decade 39 of ya product counter 4t).

In this manner the units decade 39 receives five pulses for each pulse on the lead 4 which in turn receives four pulses for each pulse on the starting pulse lead 1. Thus with the multiplier units igure set at four and the multiplicand unit set at tive a total of 20 pulses are applied through the lead 37 and amplier 3S to the unit decade 39. The capacity of the unit decade 39 is ten counts, i.e. it resets to zero on the tenth count and provides a carry pulse for the next decade of the counter. To avoid any possible interference in the various decades of the counter the carry pulses from each decade is stored in a separate carry storage circuit such as circuit 41 shown connected between the units and tens decades 39 and 42 of the electronic product counter 40. This storage circuit is cleared at the end of each series of pulses corresponding to a single pulse on lead 4. Thus at the end of the second train of pulses through the pulse generator 20 ten pulses would have been applied through the lead 37 and amplilier 38 to unit decade 39. These would result in resetting the unit decade to zero and transmitting a carry pulse through lead 43 into the storage circuit 41. The carry storage is arranged to transmit the stored carry pulse through its output lead 44 at the end of the series of pulses through the pulse generator 20 during which the carry occurred. Thus in response to a pulse from the lead 4 the Vgenerator 20 generates the nine pulses appearing on the leads 31 and then four additional pulses, the four pulses appearing on the leads 25 to 28. The pulse appearing on the lead 25 is transmitted through the cable 29 and lead 25 to the carry storage circuit 41 to trip it and cause it to transmit the stored pulse into the next counter 42. Since the pulse on the lead 25 occurs after the series of pulses used to count there is no interference in time between the actual counting pulses and the clearing pulse. The third and fourth pulses on lead 4 produce corresponding series of pulses in generator 20 and matrix 30 resulting in ten additional pulses delivered over lead 37 and amplifier 38 to the first decade 39 thus repeating one complete cycle of this decade and providing a second pulse into the tens counter 42. Without considering more this much of the circuit has multiplied the units Vdigits of the multiplier and multiplicand to provide the partial product resulting from these two digits.

Simultaneously with the transmission of pulses through the selector switch 36 pulses are transmitted through output lead 45 of the tens selector switch 35 to the amplier of the carry storage circuit 41 and from the amplifier directly to the tens decade 42. As shown, the tens selector switch is set on a second point representing 2 so that two pulses are thus transmitted directly to the amplifier of the carry storage 41 and thence to the tens decade 42 for each pulse received from the units multiplier 3. Simultaneously the pulses are transmitted to the hundreds selectorV switch 34, which is shown set at the third position to transmit three pulses per pulse, through its output lead 46 to a second carry storage circuit 47 that is interposed between the tens and hundreds decades of the counter 40. These pulses are thus fed directly into hundreds decade 50 of the product counter. The carry storage circuit 47 between the tens and hundreds decade is cleared by the second clearing pulse delivered from the pulse generator 20 through its output terminal or lead 26. At the same time, pulses are selected by the thousands selector switch 33, shown set at its number 6 position to deliver six pulses per pulse through its output lead 48 leading to a carry storage circuit 49 interposed between the hundreds decade 50 of the product counter and a thousands decade 51. Thus these pulses resulting from the units multiplier generator 3 and the thousands selector switch 33 are applied directly to the thousands decade 51 of the product counter 40.

The carry storage clearing pulses appearing on leads 25, 26, 27, and 28 are applied to the carry storage circuits 41, 47, 49, and 52 respectively in timed sequence as named so that the carries from decade to decade are correctly completed even though a nine may be registered in one of the decades in the series such that the addition of a carry pulse would cause it to reset to zero and transmit a carry pulse into the next storage circuit. Since the clearing pulses come in sequence the carry pulses produced as a result of a previous carry are thus correctly transmitted through the storage circuits to the following counter decades.

Thus in this arrangement at the end of the series of pulses delivered by the pulse generator 3 over its output lead 4 representing the units digit of a multiplier result after transmission and multiplication through the multiplicand generator and its selector switches 33 to 36 inclusive in registering the partial product of the units multiplier digit times the entire multiplicand in the corresponding decades of the product counter 40.

As the units multiplier generator 3 completes its cycle of operation and transmits a pulse over its output lead 5 to the tens multiplier generator 7 it begins its cycle of operation and generates a series of pulses corresponding to the tens digit of the multiplier and transmits such pulses through its output lead 8 to a multiplicand generator 53 associated with the tens multiplier digit. The multiplicand generator 53 is similar to the generator 20 associated with the units digit of the multiplier and generates an invariable series of pulses which after switching in a diode matrix switching circuit S4 appear on a cable 55 connected to the respective points of a plurality of selector switches 56, 57, 58, and 59. The selector switch 56 is gang connected to the thousands selector switch 33 associated with the units generator while the selector switch 57 is associated with the switch 34 and the switch 58 with the switch 35 and likewise the switch 59 with the units switch 36. The tens multiplier pulses fed through the output lead 8 and generator 53 to the selector switches result in the desired or selected number of pulses appearing on the selector switch 59 representing the product of the units digit of the multiplicand times the tens digit of the multiplier. These pulses are transmitted from the selector switch 59 to the lead 45 and thence through the amplifier of the carry circuit 41 for transmission to the tens decade 42 of the counter. Simultaneously the tens digit of the multiplicand and the tens digit of the multiplier result in pulses appearing in lead 46 from the selector switch 5S which are transmitted directly through the carry circuit 47 to the hundreds decade 50 of the product counter. Likewise the hundreds figure of the multiplicand and the tens figure of the multiplier are combined through the selector switch 57 so that these pulses appear on the lead 4S which is connected through the amplifier in the carry circuit 49 to feed the thousands decade 51 of the product counter 46. Finally the pulses representing the product of the tens digit of the multiplier times the thousands digit of the multiplicand appear on the output selector switch 56 and are transmitted through the lead 60 which feeds the carry circuit 52 for transmission into a ten thousands decade 61 of the product counter 40.

As was the case with the multiplier generator 2l) the sequence of pulses generated in the generator 53 for each pulse received over the lead S include pulses appearing at the trailing end of the sequence on leads 62, 63, 64, and 65. These output leads are connected to the cable 29, the lead 62 being conductively coupled to the lead 26 for clearing the carry circuit 47, the lead 63 being conductively coupled to the lead 27 for clearing the circuit 49, the lead 64 being coupled to the lead 28 for clearing the circuit 52, and the fourth lead 65 being connected to clear a carry circuit 66 interposed between the ten thousands decade 61 and hundred thousands decade 67 of the product counter 40. Thus the series of pulses resulting from the operation of the tens multiplier digit generator 7 and transmitted through the lead 8 result in introducing or adding into the product counter the partial product resulting from the tens Vdigit of the multiplier times the entire multiplicand. This partial product is added into the product counter as it is cornputed so as to leave the product counter at the end of this sequence of pulses with the sum of the rsttwo partial products registered therein.

The terminal output pulse from the tens multiplier digit generator 7 transmitted through its lead 9 to the selector switch 10 causes the hundreds multiplier pulse generator 11 to generate a selected number of pulses which are transmitted through the lead 12 to a hundreds multip'icand generator 68 which like the generators 20 and 53 supplies a plurality of pulses to diode matrix 69 which feeds selector switches 70, 71, 72, and 73, The switch 70 is ganged along with the switches 56 and 33 for registering the thousands digit of'the multiplicand. Likewise the selector switch 71 is ganged with the switches 57 and 34 of the hundreds digit of the multiplicand, the switch 72 is ganged with the switches 58 and 35 for the tens digit, and the remaining selector switch 73 is ganged with the switches 59 and 36 for registering the units figure of the multiplicand in the generation of the hundreds partial products. The arm of the selector switch 73 which carries pulses representing the product of the hundreds digit of the multiplier times the units digit of the multiplicand is connected to the lead 46 that feeds pulses through the amplifier and carry circuit 47 to the hundreds decade 50 of the counter 40. Likewise the output lead of the tens switch 72 is connected to the lead 48 for feeding pulses to the thousands decade 51 of the counter while the hundreds switch 71 is connected to the lead 60 to feed the pulses to the ten thousands decade of the counter. The thousands switch 70 has its output lead 74 connected to feed pulses to the carry circuit 66 for transmission into the hundred thousands decade 67 of the product counter 40.

Similar action occurs for the thousands multiplier digit lthe pulses being generated in the thousands multiplier generator 15 and transmitted through its output lead 16 to the thousands multiplicand generator 76 which like the generators 68, 53, and 20 feed pulses into a diode switching circuit 77 for energizing selector switches 78, 79, Sil, and 81 that are ganged into the multiplicand switching system representing the thousands, hundreds, tens, and units places respectively. The output of the units switch 81 is connected through the lead 48 to feed pulses to the thousands decade 51 of the product counter 40 while the tens decade S0 is connected to the lead 60 for feeding pulses to the ten thousands decade 61 while the hundreds switch 79 is connected to the lead 74 for feedmg pulses representing the thousands digit of the multiplier times the hundreds digit of the multiplicand into hundred thousands decades 67 of the product counter. The last selector switch 7S has its output connected through lead 82 and amplifier and carry circuit 83 to feed pulses into a millions decade 84 of the product counter 40. Carry pulses from the millions decade 84 are transmitted directly to a ten millions decade 85 of the counter without the interposition of a carry circuit because the ten millions decade of the counter counts only carry pulses.

The multipliers 63 and 76 also provide pulses to the carry circuits so as to clear the respective carry circuits after each series of pulses resulting from each pulse received through the leads 12 and 16. Thus the generator 68 has output leads 86, S7, 88, and 89, the lead 86 being connected in parallel or conductive relation to asoman 7 the l'e'adsnv63 and 27 for clearing the Acarry circuit V49. Likewise the Voutput lead 87 isdirectly connected to the output leads 64 and 28 Yfor clearing the carry circuit 52. Likewise the Vrlead 88 is connected to the lead 65 for clearing the carry circuit 66 while the lead 89 is connecteddirectly to the carry circuit 83. The thousands multiplier 76 has three such output leads 90, 91, and 92 that are connected in parallel with the output leads v87, 88, and A89 respectively. The fourth lead from the generatorY 76 is not required unless there are more stages to be added, that is, more digits in the multiplier factor inasmuch as the fourth lead, if used, would be for the carry circuit to operate between the million and ten millions decades 84 and 85. g

lt is also believed cear'that if more factors are t'o be accommodated in the multiplier and multiplicand that more carry circuits would be involved in each operation foreach digit ofV the multiplier and 'hence an additional number of output leads would be required from each of the multiplicand generators 20, 53, 68, and 76.

If it vbe assumed that the electronic counters in the product counter 40 have a maximum operating speed of one hundred thousand cycles perY second the operating speed of the various .pulse generators will be .limited thereby. Thus the pulses from the generators 20, 53, 63, and 76 are counted directly and therefore these pulses must not occur at a repetition rate greater than one .hundred thousand cycles per second. With the four decade capacity ,as illustrated each of these generators must generate'twelve pulses for each pulse received from the multiplier pulse generators. Thus twelve time intervals each of one-one hundred vthousandth second duration is required for each of these operations. Since the pulse generators 20, 53, 63, and 76 must each complete their cycle of Operation, generating their twelve pulses fo-r each input pulse received from the multiplier generator it jis clear that the pulses from the multiplier generators received over the leads 4,78, 12, and 16 must not occur at intervals less than twelve hundred thousandths of a second. In other words the maximum pulse repetitionjfrequenc'y of the multiplier generators must not be greater than 8,330 cycles per second. As a safety margin the -pulse generators 3, 7, 11, and should be designed to generate pulses at approximately 6,000 cycles per second. The time required 'for each of Vthe multiplier pulse generators to generate its sequence of pulsen is thus determined by its rate of approximately 6,000 cycles per second times the number of pulses to be generated. Thus if the generator is to deliver nine pulses it would require about one and one-half milliseconds or-the total time for the four .generators if the multiplier factor were 9999 would be about 6.6fmilliseconds total. Y

Any reduction in the size of the numbers'in the multiplier would of course reduce the time required for one operation. Thus if the multiplier were 1,111 it would require only eight cycles of 6,000 cycle frequency or slightly more than one millisecond for the multiplying operation.

Eight cycles are required, two from each multiplier, one over the -leadto the multiplicand generator and one t0 Y trigger the next multiplier generator.

As is conventional in the operation of electronic counters a reset circuit is provided which extends from lead 93 to each of the decades of the electronic product counter 40 and to each of its carry circuits so as to insure when the reset signal is given that each of the counter stages is set to zero and `that any carry pulses stored in the carry storage circuits are also clearedso as to prevent an erroneous indication.

The multiplier illustrated in Figure I maybe said to operate on a series-parallel method because Vthe multiplier pulses are fed through the series of multipliers in Aa serial fashion-wherein 'each of the generators generates its selected number of pulses before transmitting 'a start pulse to the succeeding pulse generator. The output pulses of the multiplier pulse generators are fed to the 'multiplicand generators and in parallel from the output of this generator through the selector switches to thecorrespending decades of the electronic counter. Thus these decades operate for the parallel reception -of information on counts thus minimizing the time required for Ithe multiplying operation. Parallel operation is not feasible for the multiplier pulses, however, because of the vastly, i11- creased number ,of carry storage circuits that would be required to keep track of `the carry track of the carry pulses and keep the various pulses properly separated. As it is set up in the circuitof Figure I this interference is avoided with the use of only one series Vof carry storage circuits between the various counter decades inasmuch as the carry pulses may bercleared after each multiplier pulse applied to the corresponding generator. Y

The circuit illustrated in Figure I avoids the use'of any switching or .gating circuits during a multiplying operation. This is accomplished without too much sacrifice in speed since the maximum computation time is in the order of six milliseconds, a time very short in comparison with the time required for, a human operator to'enter the multiplicand and multiplier factors into the vkeyboards for operating the respective selector switches. The circuit maybe simplied as far as kthe number of components is concerned by employing a stepping relay or switching or gating circuits for routing the pulses and thus repetitively use a single multiplier and multiplicand pulse generator rather than the four shown in Figure I. When Vthis is done a single multiplicand generator such as the generator 20 is sufcient and one series of output selectorswitches. It is of course necessary that the outputs of the selector switches be switched to the corresponding counter decades as the starting pulses are switched or reintroduced into the multiplier pulse generator according tol the decade place values of the multiplier. Y

A circuit arrangement utilizing this method of operation is illustrated in Figure II. While thisV system has considerably fewer components it is limited in speed by the speed of the stepping relay. In the system shown in Figure II a multiplier pulse generator 101 is provided with input Aleads 102 which are ten in number corresponding to the digits zero to 9 inclusive. The input leads 102 are connected to selector switches including a units selector switch 103, a tens selector switch 104, a hundreds switch 105, and a thousands switch 106. The output pulses from the pulse generator 101 are fed through a lead 107 to a multiplicand pulse generator 10S which generates a series of at least 12 pulses for each input pulse from the lead 107. T lie-pulse generator 10S corresponds in 4function to the generators 20, 53, 68, and 76-sho-wn in Figure I. The rst nine of the pulses generated in the generator 108 appear, two on an output iead 109, four on an output lead 110, two on an output lead 111, and one on an output lead 112. These pulses Vare Vfed into a diode matrix switching circuit 113 the output of which consists of nine leads that feed a series of selector switches including switch 114 for the thousands digit of a multiplicand factor, switch 115 for the hundreds figure or digit, switch 116 for the tens digit, and switch 117 for the units digit of the multiplicand.

The output leads .from the multiplicand selector switches 114, 115, 116, and 117 are fed through respective levels or decks of a stepping switch 11S. The output pulses from 'the units selector switch 117 ofthe multiplicand circuit transmits itspulses into a first deck o-r section 119 of the stepping switch or stepping relay 118 which in its rst po -ition transmits the pulses directly to a units decade 120 of a product counter comprising the units decade 126, a tens decade 121, a hundreds decade 122, a thousands decade 123, a ten thousands decade 124, a hundred thousands 'decade 125, a millions decade 126, and a ten millions decade 12-7.

Carry storage circuits 130, 131, 132, 133', 134,V and are interposed between the various decades of the product counter with the first of these 133interposed be-` tween the units and tens decades. Pi'here-is no suchcarry circuit between the millions and -ten millions decades since the ten millions decade counts carry pulses only.

The stepping relay 118 used in this circuit as shown in Figure 1I has a total of nine decks or separate switching levels. Four of these decks including the units deck 119, a tens deck 149, a hundreds deck 141, and a thousands deck 142 are fed from the multiplicand selector switches 117, 116, 115, and 111i respectively. The next four decks or switching circuits 143, 144, 145, and 146 of the relay are fed from clearing pulse output leads 147 to respectively of the multiplieand pulse generator 108. The pulse on the lead 147 is the same as the last of the pulses appearing on the leads 139 and 112 inclusive. The others of the output leads 14S, 149, and 150 have pulses that follow sequentially in time for a stepwise clearing of the carry circuits in progressive order so that no carry pulses will be lost if a carry pulse delivered to one counter decade should cause a carry into the next decade.

A ninth level or deck 151 of the stepping relay 118 is arranged to feed pulses from a stepping relay drive circuit 152 selectively into lead 153 feeding the tirst multiplier selector switch 103, lead 154 for the tens multiplier switch 164, lead 155 for the hundreds selector switch 165, and lead 155 for the thousands selector switch 166.

In this arrangement the stepping relay successively connects the various selector switches for the multiplier and multiplicand factors and the proper product counter decades so that the same pulse generators may be used for each of the several places in the multiplier as the operation proceeds.

As shown in Figure 1l the multiplicand selector switches are set for a multiplicand of 7,564 while the multiplier switches are set for a multiplier factor of 3,746. After the selector switches have been set to the desired multiplicand and multiplier factors a multiplication operation is started by momentary depression of a start button 161i. The start button 168 by means of a circuit illustrated in Figure 111 produces a reset pulse on a reset lead 161 that is fed to each of the counter decades as Well as the carry circuits therebetween for resetting the counter and the carry circuits to zero in anticipation of or preparation for the multiplying operation. This cancels any previous computation results. At the start of an operation the stepping relay has its contacts one step behind the position shown in the drawing. That is the movable contact of the deck 151 is on an idle contact 162 and the other decks correspondingly positioned. The initial pulse provided by the start button 169 causes the iirst stepping operation of the stepping relay to advance all of the contacts to the position shown in the drawing and at the conclusion of such advance transmits a start pulse through the deck 151 and lead 153 to the selector switch 103 thereby feeding the pulse into the pulse generator 101 at the number six position. As this pulse is transmitted from oscillator to oscillator through the pulse generator 161, which comprises a series of single cycle oscillators, six pulses are delivered on the lead 167 and the final pulse or seventh pulse is delivered through an output lead 163 to the stepping relay circuit 152. Each of the six pulses delivered over the lead 107 from the pulse generator 101 in response to the signal received on the number 6 terminal produces a complete cycle of operation through the pulse generator 108 thereby delivering the predetermined number of pulses through the diode matrix to energize the multiplicand selector switches 114 to 117 inclusive. Thus each of the six pulses delivered through the lead 107 after transmission through the generator 1113 produces four pulses on the output selector switch 117 for the units decade of the product counter. These four pulses are thus countered in the units stage and there being four such pulses for each of the six transmitted through the lead 107 provides a total of twenty-four pulses or the first of the partial products in the units stage.

These twenty-four pulses causes the units counter 121) Vto count toten twiceA and each time transmit its carry pulse to the carry storage circuit 130. The carry storage circuit 136 is cleared at the end of each cycle of operation of the generator 108 by the voltage pulse delivered on the lead 147. Thus the conclusion of the six pulses on the lead 197 provides a total of twenty-four pulses in the rst decade of the counter.

Simultaneously pulses per pulse are delivered through the tens selector switch 116 and the carry circuit to the tens decade 121. These pulses are in addition to the carry pulses and thus provide the partial product of the units multiplier factor times the tens multiplicand factor plus the carry from the units decade this being stored in the decade 121. At the same time live pulses per pulse are transmitted through the multiplicand selector 115 and switch-ing level 141 and carry circuit 131 to the hundreds decade 122. And finally at the same time the thousands selector switch l1-l receives its seven pulses per input pulse on the lead 197 wh-ich are counted in the thousands decade 123. rihis completes the registration of the rst of the partial products resulting from the multiplication of the multiplicand times the units ligure of the multiplier.

At the conclusion or the six pulses, the seven pulse delivered through the lead 153 causes the stepping relay to advance one step and thus provide a starting pulse which is fed through the lead 15dand the tens selector switch 104 into the pulse generator 161. This connection provides four pulses on the lead 107. At the same time the stepping switch has advanced all of its contacts corresponding to the decades or levels 11'?, 14%, 141, 142, 143, 144, 145, and 146 to the next step so as to effect the equivalent of a column shht or register shift so that 'he units switch 117 of the multiplicand is now connected to feed pulses into the tens decade of the product counter. The stepping relay also effects the proper switching for the remaining selector switches of the multiplicand circuit as well as the clearing pulses for clearing the carry storage circuits.

The remaining digits of the multiplier are handled in the same way since at the completion of each series of pulses the stepping relay is advanced to the next step in its cycle of operation. The linalstep `after completing the thousands digit of the multiplier brings the wiper or movable contact of the deck 151 back into contact with the idle contact 162. Since the output pulse of the stepping relay is then delivered to an idle contact the complete operation stops with the product then totaled and indicated or registered in the various decades making up the product counter.

The timing of the pulses in the stepping relay is such that the output pulse delivered through the deck 151 occurs after the Wipers or movable contacts of the other decks are all rmly in place and connected to the respective counter decades. ri`hus except for failure of contacts due to mechanical wear or dirt there can ce no loss of pulses through the circuits.

The speed of operation of this circuit is determined almost entirely by the stepping relay since the time required for the generation through the generator 161 of nine pulses plus the output pulse on the lead 163 is ten cycles at a 6,000 cycle per second repetition rate which is one six hundredth of a second. Since the stepping relay requires a minimum of approximately one-sixieth of a second it is clear that the electronic portions of the circuit require only ten percent of the time per step and thus the stepping relay operates at practically its maximum or free running stepping speed which for ordinary stepping relays is in the order of 50 to 60 steps per second,

The drive circuits for the stepping relay operation are illustrated in detail in Figure lil. As shown in this tigure. the stepping relay is provided with a ratchet wheel 165 that is mounted on a shaft 166 which may preferably carry the movable contacts or wipers of the van-ions decks l1 or levels of the stepping relay illustrated in Figure Il. 'I 'he stepping relay is advanced stepwise by operation of a pawl 167 that is urged in stepping direction by a spring 168 and which is cocked or preset tooth by tooth by operation of a solenoid 169 cooperating with an armature 170 upon which the pawl 167 is mounted. 'Ihe armature 170 also carries an extension 171 having contact elements 172 and 173. The contact element 173 cooperates with the contact element 174 mounted on a resilient leaf 175. Contact element 176 also mounted on a leaf 175 cooperates with a stationary contact 177.

l When the start button 160 is in its normal or undepressed condition as illustrated in Figure III is connects, through its normally closed contacts, a condenser 180 between a B+ lead 181, also connected directly to the exible leaf 175, and a grounded lead 182. A small resistor 183 is included in this circuit to limit the peak amplitude of the charging current through the condenser 180. Thus the condenser 180 is normally held in its charged condition. When the push button 160 is depressed it closes its normally open contacts 184 thus permitting the condenser 180 to discharge through a resistor 185. The junction between the contacts 184 and resistor 185 are connected to the reset lead 161 and the momentary voltage developed across the resistor 185 provides the reset voltage for resetting the product counter. Simultaneously the voltage developed across the resistor 185 by closure of the contacts 134 provides a voltage pulse whichV is transmitted through a diode rectifier 190, condenser 191, and resistor 192 to the grid circuit of a thyratron 193. The thyratron 193 includes the solenoid 169 in its plate circuit so that when it tires it energizes the solenoid. The plate circuit for the thyratron 193 may be traced from the B+ lead 181, through the exible leaf 175, contacts 176 and 177, lead 194 connected to the solenoid 169 and thence through the coil of the solenoid to an anode 195 of the thyratron 193. Cathode 196 of the thyratron 193 is connected directly to the grounded lead 182. A grid 197 of the thyratron 193 is normally biased to cut ot voltage or beyond cut ot voltage by bias voltage supplied through a resistor 198 and grid current limiting resistor 199.

When the voltage impulse obtainedfrom the starting button contacts 184 is applied to the grid circuit of the thyratron the thyratron tires or conducts current and this current ow through the solenoid 169 draws the armature 170 downward, as shown in the gure, thereby bringing the contacts 173 and 174 together and by the force egterted on these contacts separating the contacts 176 and 177. The closure of the contacts 173 and 174 connects a condenser 200 through current limiting resistor 201, arm 171, and contact 173 to the B+ lead thus charging the condenser 200 to the B+ potential. The opening of the contacts 176 and 177 opens the anode circuit to the thyratron 193 thus allowing it to deionize so that its grid 197 may regain control and hold the thyratron in nonconducting condition. The deionization of the thyratron is aided byV a diode rectiiier 202 that is arranged to short circuit the coil of the solenoid 169 and thus absorb the inductive voltage that is generated in the solenoid coil when the current flow is interrupted.A With the current flow through the solenoid 169 interrupted, the armatureV 170 is` released allowing the spring 163 to advance the ratchet wheel 165 one step and thus at the completion of such step bring the contact 172 back into contact with its mating contact 203. This completes a circuit from -the condenser 200 through the now closed contacts 172 and 203 to an output lead 204 that feeds the ninth level 151 of the stepping relay 118 and thus provides the signal to the pulse generator for tripping it into a cycle of operation according to the setting of the then connected multiplier selector switch. The last pulse from the generator on lead 163 is fed to the thyratron grid circuit to lire the thyratron and thus advance the stepping relay. Y

This circuit thus provides the time delays and timing sequence required in the multiplying circuit shown in Figure II since the last pulse generated by the multiplier pulse generator is fed through the lead 163V to trip the thyratron 193 thus causing a stepping operation by cocking the stepping or return spring 16S and at the same time charging the condenser 200 so as to provide the voltage pulse at the completion of the operation.

False resetting of the counter in response to the pulses delivered over the input lead 163 and possible feedback through resistor 192 and condenser 191 is prevented by the diode rectifier 190 and the relatively low resistance of the discharge resistor 185.

False operation due to the possible bouncing or intermittent contact of the contacts either in the start switch or starting key or the contacts 172, 203 is prevented by connecting these contacts in the circuit in such a way that when they are driven to one limit of their travel the condenser is charged to the voltage required for the signal pulse and then when the contacts return to their other lirnit o-f travel the condenser is discharged through a circuit having a very short time constant. The discharge of the condenser provides the output signal during the initial contact and the repeated closure on the bouncing of the contacts is without eiect because the condenser or condenser 200, as the case may be, is then completely discharged.

The multiplier pulse generators 3, 7, 11, 15 or 101 are preferably constructed of a plurality of single cycle oscillators arranged to execute their cycles of operation successively each being triggered or startedV from the preceding oscillator. These oscillators may take several forms, the preferred form being a chain of blocking oscillators, a variety of oscillator in which the oscillator tube is normally biased to current cut on?, and the grid circuit is inductively coupled to the plate circuit so that in response to a voltage impulse one cycle of oscillation will be completed and the tube will then return to its quiescent or nonoscillating condition and wait for the next starting impulse. The circuit arrangement used in these multiplier generators is illustrated in Figure IV. As shown in this figure the input pulse either from the starting or input lead 1 or from the preceding pulse generator or from the leads 153, 154, 155, or 156 is fed through an input lead 210 as shown in Figure IV and by means of a switching contact arm 211, representative of a multiplier selector switch, is directed to one of a number of input terminals marked from Zero to nine inclusive. These terminals constitute separate inputs to various stages in the blocking oscillator chain. Each blocking oscillator consists of a single triodc 212 having a plate 213, grid 214, and a cathode 215. The plate 213 and grid 214 are inductively coupled through a transformer 216 having a grid winding 217 and a plate windin-g 218. The plate winding 218 is connected between a B+ lead 219 and the plate 213 of the tube and is in parallel with a damping resistor 220. The grid winding 217 of the transformer is connected between the 'grid 214 and a bias resistor 221 that is connected to a bias lead 222 maintained suiciently negative with re- Spect to ground so that the tube will not normally draw `any current.

All of the oscillators are similar in that they have the elements just described and all have Ytheir cathodes connected in parallel, except for the tenth stage, and have these cathodes returned to ground through a cathode resistor 223. The output pulses are taken from the common cathode connection through an output line 224 that is representative or" the output leads 4, 8, 12, and 16 ot Figure I or theV output lead 107 of Figure 11. The tenth oscillator of the chain has its own cathode resistor 225 so as to deliver a single triggering pulse from its cathode through an output lead 226 which serves to supply the input signal for the next multiplier generator in the circuit shown in Figure I or the impulse for the stepping relay as transmitted through the lead 163' of Figure II. in addition each stage or oscillator has a coupling condenser 227 connected between its plate 213 and the resistor end of the grid winding of the next transformer for the next stage.

In the operation of such a circuit a positive voltage pulse applied through one of the input terminals from the switch 2li causes a momentary positive voltage 'to be transmitted through the grid winding as a conductor to the grid 214 of the tube thereby causing the tube to draw plate current. The initial plate current of relatively small magnitude generates through the transformer a positive voltage on the lead connecting the grid winding to the grid so as to drive the grid of the tube further in a positive direction thereby increasing the plate current. This action is cumulative as long as the plate current can increase and generate grid voltage. As soon as the circuit saturates with full current owlng through the tube and the cathode resistor 223 there is no longer any increase in current flow and hence no Voltage generated in the secondary winding or grid winding of the transformer. The grid thereupon loses its positive voltage and cuts oi the flow of current through the tube thus terminatlng the cycle of oscillation. The resulting positive pulse of voltage appearing at the plate of the tube as the current flow is cut olf is transmitted through the coupling condenser 227 and serves as a triggering impulse to start the next oscillator.

in this arrangement the number of pulsesdelivered to the output lead 224 depends upon which stage ofthe series of blocking oscillators is selected for the introduction of the starting pulse. If the pulse is introduced into the left-hand stage, the one marked 9, all of the `blocking oscillators execute one cycle of oscillation in sequence thereby delivering nine pulses on the output lead. However, if the input pulse is applied say at the number 2 terminal only the last three of the blocking oscillators operate thereby delivering two impulses in the output lead 224 and the single impulse on the output lead 226. Thus the number of impulses to be generated for each incoming impulse is controlled by merely selecting the point in the chain at which the incoming pulse is applied.

While blocking oscillators are preferred as a simple form of pulse generator other types of single cycle oscillation generators may also be employed. The only requirement is that each generator or each oscillator deliver one cycle and at the close of its cycle of operation produce an output pulse which may trigger the succeeding stage of the chain.

The multiplier pulse generators as illustrated in 'Figure IV are not suitable for use in a parallel operation because each generates a series of pulses corresponding to the input terminal selected for the introduction of the input pulse. For parallel operation it is necessary that an invariable number of pulses be generated for each input pulse and that switching means be employed on the output side of the pulse generator for selecting the desired pulses according to the multiplicand factor. A pulse generator suitable for use in the multiplicand'portion of the circuit shown in Figure I or Figure II is illustrated in Figure V. In common with Figure IV, Figure V shows a chain or series of blocking oscillators except that all the oscillators rather than a selected number are used each time.

In this circuit twelve blocking oscillators are employed, each being like the others except for the cathode connections. Each of the oscillators comprises a triode section 230 of a dual triode tube having a plate 231, control grid 232, and cathode 233. The cathodes are connected, either singly or in combination with cathodes of other oscillators of the chain, through cathode resistors to ground. Cathode resistor 234 serves the rst two oscillators of the chain. The control grid 232 and plate 231 are incluctively coupled through a transformer 235 across its cathode resistor.

having a grid or secondary winding 236 and a primary or plate winding 237. The plate current for the tube is obtained from a B-llead 238 the circuit bengffrom this lead through the primary winding 237 of the transformer 235, through the tube plate 231 to cathode 233 and thence through the cathode resistor 234 to grounded lead 239. The primary or plate winding 237 of the transformer is paralleled with a damping resistor 240. Grid bias to maintain the tube at 'current cut oi is obtained from a bias line or bias lead 241 through a grid biasing resistor 242 that is connected to one end of the secondary or grid winding 236, the other end of the winding being connected to the grid 232. Starting pulses for the pulse generator are introduced through an input lead 243 and condenser 244 that is connected to the junction between the resistor 242 and the grid winding 236 of the transformer 235. An output pulse from the plate circuit of the iirst oscillator stage is taken through a coupling condenser 245 to the resistor end of the secondary or grid winding of the transformer for the nextoscillator stage.

As described in connection with Figure IV a positive voltage impulse applied to the coupling condenser 244 causes the tube to draw current from the B-llead 238 through the primary winding 237 of its transformer 235 to the tube. As long as such current ow is increasing a voltage is generated in the secondary winding 236 tending to drive the grid positive and maintain the current flow. As soon as the tube saturates or draws its maximum current the current increase is stopped and hence there is no Yvoltage generated in the secondary winding` 236 and the grid immediately returns to its negative potential relative to ground thus cutting off current ow through the tube. The cut off in current causes a sharp positive rise in voltage at the plate 231 Vwhich is communicated through the coupling condenser 245 to start the next stage into its cycle of oscillation.

As each stage in the chain of oscillators undergoes its cvcle of oscillation a positive voltage pulse appears Thus the rst pulses from the rst and second oscillators appear across the cathode resistor 234 and are fed out through an output lead 246 leading to a diode matrix circuit 247. The nextV four oscillators in the chain have their cathodes tied together and to the grounded lead 239 through a common cathode resistor 248 thus providing four impulses that are transmitted over an output lead 249 to the diode matrix circuit 247. The seventh andl eighth oscillators of the chain have their cathodes tied together and to ground through a resistor 250 and are connected through lead 251 to the diode matrix circuit 247.

The rninth oscillator of the chain has its own cathode vresistor 252 and the voltage at the cathode of this stage is transmitted through a lead 253 to the diode matrix circuit and also through an output lead 254 which leads to the rst carry storage circuit. The last three oscillators of the chain have individual cathode resistors 255, 256. and 257 and the cathodes of these stages are connected to output leads 258, 259, and 26% which correspond respectively to the output leads 147 to 150 inclusive of Figure II.

which may be combined by suitable switching circuits to provide selectable numbers of pulses per input pulse received on the lead 243 as well as a series of individual pulses following the others in time and suitable for clearing the carry circuits employed between the stages of the electronic counter into which the pulses are being transmitted for registration.

'The diode matrix 247 is representative of the diode matrix circuits 30, 54, 69, and 77 shown in Figure I and the diode matrix circuit 113 shown in Figure II. In each case the circuit comprises a number of diode rectifier or semi-conductors that are arranged to connect the various leads` from the multiplicand pulse generators The chain of oscillators thus delivers av -total of nine pulses on the leads 246, 249, 251, and 253 'aser-116e Y to nine output leads which feed the nine 'terminals of the selector switches used for selecting the multiplicand factors.Y As Vshown Yin Figure lV the output lead 253, which carries one impulse per generator input pulse is connected directly to a first selector switch lead 265 which is connected directly to the number 1 terminal of each of the selector switches associated with the multiplicand generator. This same output lead 253 istcon- Vnected throughrdiode rectifiers 266,267, 268 and 269 4to output lead 270, representingthe number three terminals;` lead 271 representing the number five terminals; lead 277 representing the number seven terminals; and lead 278Arepresenting the number nine terminals. Y,

The vmultiplicand output lead 251 from theseventh and eighth oscillators of the chain, which carries two pulses vper input pulse, is connected directlv to selector switchlead` 274 so as to supply this lead with two pulses per input Vpulsevand is connected through rectifier 275 to'supply two pulses to the number three lead 270 which lin combination with the one pulse from the lead 253 makes three pulses for this lead. Thelead 251 is'also connected through rectifier 276 to `supply two pulses per input pulse to the number siX switch leadr277.Y

Output lead 249 of lthe multiplicand generator which 'carries four pulses per input pulse is connected directly Yto selector switch lead 278 representing the number four position and is connected through rectifier 279 to supply four pulses to the number five selector switch lead 271. This lead 249, carrying four pulses, also feeds through rectifier 280 into the number six switch lead 277 thus providing in combination with the two pulses through the rectifier 276 the siX pulses required o n this lead. The lead`277 is connected through rectifier 281 to' feed six pulses per input pulse into vnumber 7 output lead 272 which in combination with the single pulse transmitted 'through the rectifier 278 makes up sevenspulses per input pulse for this lead. The six voltage pulses appearing on the lead 277 are also transmitted through rectifier 282 into number eight selector rswitch lead 283. The other two pulses to makeup theeight pulses for this lead are obtained from the first two blocking oscillators through 'lead 246 and rectifier 284. The rectifier l284 is provided to Yprevent any loading on the lead 283 because of the vrelatively low resistance of the cathode resistor 234. -Finally the number nine output lead 273 receives eight lpulses from the number eight lead 283 through rectifier 285 which yin combination with the single pulse obtained through rectifier 269 make up; the nine pulses per input 'pulse for the selector switch lead 273. Y i Y The output impedance of the various groups of oscillator stages as represented by the resistance of the cathode resistors 234, 248, 250, and 252 is low enough compared to the input impedance of the carry circuit amplifiers to which the impulses are transmitted so that any reason- 4able number of selector switches may be connected in parallel to the 'matrix output leads and thus provide the pulses for the various stages of the productcounter.

VThe essential difference between this pulse generator and the one illustrated in Figure IV is the fact that the preceding one, Figure IV, generates only a selected number of pulses which varies according to the selector switch position whereas the generator shown in Figure V generates an invariable Vnumber of pulses and the selection is made on the output side where several switches may beconnected in parallel to feed selected numbers of pulses into various decades of the electronic counter used to count the pulses representing the product of the multiplication. Y

In the circuits shown in Figures I and II the output pulses from the multiolicand selector switches were transmitted through amplifiers and carry storage circuits into the respective decades of the product electronic'counter. Where there is no preceding or lower order decade an amplifier only is required between the selector switch and the `counter decade. Wherever there is simultaneous tor possibility of simultaneous entry of data from carry pulses from -the preceding decades and pulses from selector switches the carry storage circuits must be em- 290 from a selector switch 291 which is representative of any of the multiplicand selector switches shown in Figures I and II. The positive pulse of voltage on the lead 290 is transmitted through a coupling condenser 292 and diode rectifier 293 to a control grid 294 of a pentode amplifier having its plate 295 connected to a B+ lead 296 by way of a plate resistor 297. The amplifier has its cathode 298 and suppressor grid 299 connected directly to a grounded lead 300. The amplifier grid 294 is biased to plate current cut off by a grid leak resistor 301 that is connected to a bias voltage lead 302 that is maintained approximately 8 volts negative with respect to ground by voltage divider resistors 303 and 304 connected between the grounded lead 300 and a source of negative potential of approximately 16 volts employed in the pulse generator circuits. The amplifier serves as a phase reversing device to convert the positive voltage pulses received from the multipliers through the selector switches into negative pulses suitable for operating an electronic counter of the type illustrated in U.S. Patent No. 2,521,- 788. The negative voltage pulse from the plate 295 of the amplifier is clipped at a predetermined level determined by resistors 305 and 306 connected between the B+ lead and ground. The clipping is accomplished by a rectifier 307 connected between the output lead from the plate 295 and the midpoint between the resistors 305 and 306. The resistor 306 is by-passed with a condenser 308 to reduce the apparent impedance at this junction. There is an amplifier such as the one just described for each of the decades in each of the electronic counters illustrated in Figures l and II.

A carry pulse storage circuit is associated with each of the amplifiers used between the electronic counters for storing the carry pulses until the completion of the cycle of operation of the multiplicand generator in response to each pulse received from the multiplierV generator. These storage circuits are similar to the one illustrated in Figure Vl and comprise a dual triode 310 connected in a bistable multivibrator circuit similar to a conventional binary counter circuit. lnY this particular circuit arrangement cathodes 311 and 312 of the double triode are tied together and connected to ground through cathode resistor 313 and cathode by-pass condenser 314. Plates 315 and 316 are connected to the B-llead 296 through plate resistors 317 and 318 respectively.

Control grids 319 and 320 cooperating with the cathodes 311 and 312 respectively aretconnected to ground through grid return resistors 321 and 322 and are each tied to the opposite plate through plate to grid resistors 323 and 324 the latter two resistors being by-passed by condensers 325 and 326 respectively. The grid resistor 322 is returned to the reset circuit rather than directly to ground. The reset lead is connected'to ground through a low resistance usually in the order of 200 to 500 ohms and may be considered as grounded except for the reset voltage applied momentarily during Vresetting of the circuits.

`the plate to grid resistors 323 and 324, and 100,000 ohms for each of the grid to ground resistors 321 and 322. The cathode resistor for. this set of values should be in the order of 12,000 ohms. The plate to grid condensers should be in the order of 50 micro-microfarads and the cathode condenser may be .0l microfarad or larger.

With these values the circuit is bi-stable in that if the Ivgrid 320 is driven positive, as by a reset pulse, current will l? flow through the plate resistor 318, through the tube and cathode resistor 313 in an amount suflicient to drop the potential of the plate 316 and drive the grid 319 of the other triode section negative to current cut ott. The

18 stages connected according to the disclosure of U.S. Patent No. 2,521,788. Each decade consists of four Hip-flop or binary stages one of which is illustrated in Figure Each stage comprises a dual triode tube 341 that -has its resulting potential increase at the plate 315 coupled grids and -plates cross connected to provide bi-stable ,opthrough the coupling resistor 324 holds the grid 320 at eration. The circuits for the tube comprise a` common cathode potential so as to maintain the current flow. Any plate resistor 342, individual plate resistors 343 and 344, pulse that cuts oi the current iiow momentarily causes individual grid to plate resistors 345 and 346, grid to current to flow, after the pulse through the plate 315 and ground resistors 347 and 348 as well as cathode resistor cathode 311 to reverse the condition of current flow. 349 vand cathode condenser 350; The plate to grid re- Negative voltage pulses representing the carry from sistors 345 and 346 are lay-passed with small condensers an associated decade of the product counter are carried or 351 and 352. transmitted over a lead 330 and series connected con- The plate resistor 343, the plate to grid resistor 345, and densers 331 and 332 to momentarily drive the grid 320 the grid to ground resistor 347 are connected in series 'benegative. Momentarily driving this grid negative cuts tween the resistor 342 and ground. Similarly the plate reoi current ow through the plate resistor 318 thus apsistor 344, plate to grid resistor 346, and grid resistor 348 plying a positive voltage to the coupling resistor 323 and are also connected in series and connected between the condenser 325 to drive the grid 319 of the other triode common plate resistor 342 and ground by Way of the reset section positive and thus establish current flow through circuit as indicated by lead 353 (Figure VII). The cirthe left-hand section of the triode. This is the Storage cuit values for this circuit are the same as those indicated condition of the tube with the carry pulse or carry infor the corresponding elements in the circuit `associated formation stored therein. The input circuit is stabilized with the dual triode 310 shown in Figure VI. The tube so as to ralways respond to the negative counter carry operates with one side or the other conductingfcurrent pulses by a parallel combination of a resistor 333 and and the other side cut off. The condition of current conrectier 334 that are connected between the junction of duction can be variedV or changed from one side to the the condensers 331 and 332 and ground. The rectier other by negative voltage pulses applied through an input is polarized so as to shunt any positive voltages appearing condenser 354 connected tothe common plate resistor 342 at the junction of the condensers to ground while permitso as to simultaneously drive the plates ,of the tube negating negative voltage pulses to be transmitted directly to tive momentarily to cut ol current flow. The charges the grid of the tube. on lthe platey to grid condensers when the pulse disappears At the end of each series of pulses generated in the causes the previously nonconducting side of the tube to multiplicand pulse generator a separate carry storage conduct current. Thus the cycle of operation is comclearing pulse is generated for each ,carry circuit. Such pleted by two pulses and the tube acts as a scale of two a pulse is .delivered over lead 325 and series connected counters. Output pulses to drive the next stage of the condensers 336 and 337 to the grid 319 of the dual triode counter are taken from the junction between the plate and 310. In order to minimize the number of components Yin plate to grid resistors 344 and 346 through a condenser the multiplicand pulse generator the ninth oscillator is 355 which may serve the next stage in the same capacity used to feed a pulse into the diode matrix shown in as the condenser 354 serves the rst. The potentials at Figure V as Weil HS to the rSt of the Carry Storage CI- the plates of the triodes are taken through output leads cuits. Therefore it is necessary that the carry storage including series resistors 356 and 3-57 to indicating mechcircuit respond to the trailing edge of the pulse rather anism that may be neon lamps or other voltage sensitive than the leading edge so as t0 avoid interference between indicating devices to indicate the state of conduction of the the last counting pulse and the clearing pulse. This is dual triode 341, accomplished by lJY-P'eSSne the Positive Portion of the As indicated in the patent above referred to certain pulse i0 ground through I'eCtlerS 338 Which S in parallel 45 feedback Connections comprising series condensers and with resistor 339 and connected to the junction between resistors are Connected between the certain plates O f the the condensers 336 and 337. Thus as the voltage on the third and fourth stages of a binary decade to control lead 335 goes positive current ow through the condenser grids of the second and third stages respectively so as ,to 335 end rechne? 3 33 to ground Charges the Condenser 336 arbitrarily feedback certain pulses resulting from ,opera- Wlthout runslnlhng 211 appreciable Voltage Pulse t0 the D0 tion of the third and fourth counter stages to reset the gfld of the 'lube 0n the return to Zero, the milling edge, second and third stages and thus cause a complete cycle of the Cleaflhg Pulse from the Pu15e geuefaol. the luncof operation to be accomplished with ten input pulses hou between the. C Ohdehsefs 336 and 337 1S dllVen nega rather than the sixteen tha-t normally would be required uve 'Chus tfansnuhng a uega'uve Signal through the Cou" for complete cycling of a four stage binary counter. i denser 337 to gld 319 to Cause Current out off in the The indicating mechanism for the electronic counter is left-hand SeClon of the ube- T1115 Curl'eut out off results not illustrated because various conventional types of well 1n a positive voltage pulse at the plate 315 which is transknown .indicating equipment may be connected to the mined through a Coupling Coudellse1 n 340 to grid 294'of counter depending upon the type of outpu-t indication dethe amphhel t uhe thuS dflVlng the glld PoSflVe to PloVlde sired. These may include neon glow tubes connected vto the negative's1gnal on its plate 295 which is delivered aS 60 the counter, or various types of stepping switches or simia counting slgnal into the next decade of the counter. lar devices that assume dierent positions according to The clearing pulses received over the lead 335 do not the count stored in a counter. produce a pulse yat the plate 315 unless a carry pulse has The multiplier pulse generators illustrated in Figures I previously been received in order to trigger the tube into and II and in detail in Figure IV employ electronic tubes the condition with the left-hand side conducting current. as the amplifying elements for each of the oscillators. A If the left side is nonconducting the negative pulse merely similar pulse generator may be constructed using resistincreases the negative grid bias without producing any ances, condensers and transistors. Such a circuit is illuscurrent changes in the tube and thus no output signal. trated in Figures VIII and VIIIa. Such a circuit kcom- Thus the carry storage circuit transmits a pulse to the next prises a chain of individual oscillator stages all of the counter only in the event that it has received a carry 7o stages being similar and arranged so that the output pulse pulse from the preceding counter subsequent to the last resetting pulse or the last clearing pulse.

The electronic counters illustrated in Figures I and II as registers for the product of the computation are conventional decades each consisting of four binary ip-op 7 from each stage Vmay serve as the input pulse for the next. Each stage comprises a transistor having a base 360, a collector electrode 361, and an emitter electrode 362. The base 360 is connected through a 3,000 ohm resistor 5 363 to a grounded lead 364. The collector electrode 362!s is connected through a load resistor 365 of 3,000 ohms to a negative supply lead maintained at approximately minus 25 volts.i 'The emitter electrode 362 is-connected directly to ground through a small condenser 366 of approximately 500 micromicrofarads. The emitter is also connected to an output lead 367Y through a small coupling condenser '368, the output lead 367 being grounded through a resistor 369 which with the condenser 368 provides a time constant short in comparison with the time of one cycle of each of the transistor stages. The emitter is supplied with voltage at approximately minus l volts through a resistor 369 of approximately 5,500 ohms. Input pulses from a lead 370 are transmitted through selector switch 371 to a selected one of the bases 360 of the various transistors according to which of the stages is to be initially energized. Likewise, a trigger voltage of each stage, which is developed across the load resistor 365, is applied through a coupling condenser 372 to the base of the next transistor stage.

Normally the emitter is biased suflicently negative so as to inhibit current ow through the transistor from its base to its collector electrode. Upon the application of Va negative pulse of voltage to the base 360 the bias between the base and the emitter is reduced to a point where the emitter draws-appreciable current. This current supplied by the condenser 366 results in a much larger current ow from the base to the collector thus resulting in a continuing negative voltage applied to the base 360 thus holding the bias at a low value. As the emitter draws current from the condenser its voltage drops or goes negative thus resulting in decreasing the current flow through the transistorresulting in a positive going voltage appearing at the base and a negative going voltage appearing on the collector electrode. With the combination of values shown the action is regenerative or of a trigger nature in that little current ows in the collector circuit until the emitter bias is reduced by the negative voltage supplied to the base. When this occurs the current ow through the base to the collector suddenly increases and the current flow from base to emitter suddenly rises to a large value by the amplifying action resulting from the changes in voltage at the electrodes.

Then as the emitter current decreases as the condenser 366 is charged by current tiow from the emitter, the current ow decreases until suddenly it reaches a critical point when it is cut off suddenly to zero value.

' The negative voltage impulses at the emitter electrode are transmitted through the coupling condenser 368 to the voutput lead 367 and since the time constant of the condenser 368 and the common grounding resistor 369 is small compared to the time constant resulting from the ow of current to the condenser 366 this circuit has the VVeffect of diierentiating the emitter voltage signal thus producing a peaked wave form suitable for use with the counter. This' wave form is transmitted to the counter after ampliiication and serves to drive the counter a number of steps depending upon how many of the transistor stages was included and operated by each impulse from the scale. As before, the selector switch such as the switch 371 is included to transmit the impulse from the preceding generator to the selected one of the transistor stages. Likewise the output from the number l transistor stage,'the 'last' one in the chain, is fed back through Vthe last or zero switch 'point to the iirst or number 9 stage of the following pulse generator.

VFigure VlIIa illustrates the relationship between the emitter voltage and emitter current. As shown in this gure with a load line such as a line 374 drawn to correspond to the resistance of the emitter resistor 369 the Y static or stable operating condition occurs at a point P with the emitter drawing a slight negative current and the collector'current cutoff. The input voltage pulse Y applied tothe base has the effect ofmornentarily reducing t 20 Q. After passing the point Q the current suddenly rises because of the amplifying action of the transistor and the current throughv the emitter and collector increases until limited by the circuit elements at a point R on the characteristic curve. At this time the emitter is drawing a Yrelatively heavy current, the current owing from the base to the'emitter to charge the condenser 366 in the negative direction so that the operating point then follows from R along the curve to a second critical point at the valley marked S. Upon reaching this point the emitter condens; er 366 is charged to a .higher negative voltage and this is suicient at the reduced collector current to cause the transistor to suddenly cut off and the operating point then followsY trigger-.wise fromthe point S to a point on the characteristic curve below the point P. The circuit then returns to a stable state, with the transistor drawing a slight negative current, at the point P. Thus for each voltage pulseV applied to the base of the transistor the transistor executes one cycle and transmits an output pulse to the counter and another pulse to the following transistor stage of the chain so that the following stage can then generate its pulseY and so on to transmit the pulse YEach of the multivibrator stages including its twin triode tube consists of a pair of cathodes 390 and 391 connected in parallel through a cathode resistor 392 to a grounded return lead 393 that is common to all of the stages. Each of the triodes also includes a plate or anode 394 cooperating with the Vcathode 390 and a second anode 395 cooperating with the cathode 391. Control grids 396 and 397 cooperate with Ycathodes 390 and 391 respectively. The'anode 394 is connected through a resistor 398 of approximately 100,000 ohms to a B+ supply lead 399. Likewise the anode 395 of the second half of the triode is connected through a 50,000 ohm resistor 400 to the supply lead 399. yThe control grid 396 cooperating with the cathode 390 is connected through a 500,000 ohm resistor 401 to the grounded leadY 393-while the second control grid 397 is connected through a one megohm resistorV 402 to the positive supply voltage lead 399. The anode 394 is further'connected by a 1,500 micro-micro- .fa'rad condenser 403 to the control grid 397. Furthermore,`the cathodes are connectedY through a 100 micromicrofarad condenser 404 to a common output lead 405 which is grounded through a 100,000 ohm resistor 406. The output lead 405 is connected to the corresponding multiplicand generator in a circuit as shown in Figures l or II.

Each-oli the multivibrator circuits is coupled to the next inthe chain by a 33 micro-microfarad condenser 407 Which serves to connect the second grid -397 of one stage toa first grid (corresponding Yto the grid 396) of the following stage.

Input pulses from the start key or a preceding multiplier aresupplied through alead 411 and a coupling condenser 412 to the moving arm Y413` of a multi-point selector switch and from the taps of the switch through a lead 414 to the number 9 stage grid 396 or through lead 415 to the number 8 stage or through corresponding leads to the other stages of the oscillator chain. Thus a number of stages of the roscillator chain are included depending upon the'selection made through the switch 413. j

The number 1 stage comprising the dual triode 388 has an Voutput connection 420 connected through Va lead 421l an output lead 414 to the input switch of the next multiplier. As in the preceding circuits should the value for this particular multiplier be selected as zero the start impulse or the pulse in the preceding multiplier is transmitted directly through the switch to the output connection 414.

In this particular circuit the output lead 405 to the multiplicand generator has a pulse of voltage appearing thereon as each of the multivibrators goes through its cycle of operation. In the quiescent or stable state each of the multivibrators is drawing current through its right hand section as illustrated in the drawing which for the number 9 stage comprises the resistor 400, plate 395 and cathode 391. This ow of current, since the control grid 397 is drawing current through the one megohm resistor, is determined almost entirely by the magnitude of the resistors 392 and 400. The application of a positive pulse of voltage to the control grid 396 causes current tlow through the left half of the triode which by the amplifying action produces a negative going signal at the plate 394 which coupled through the condenser 403 drives the second or right half control grid 397 negative so as to cut off the ow of current through the second half or right-hand section of the tube. This results in the lefthand section of the tube drawing current at a rate determined by the 100,000 ohm plate resistor 398. The current flow through the tube under this condition is about half of what it was under the prior state. When the condenser 403 is charged through the resistor 402 so that the second half of the tube again draws current the tube quickly returns to its initial state thereby increasing the current ow through the cathode resistor 392. This positive increase in voltage resulting from the increased current appears on the output lead 405 as a short duration pulse determined in time by the time constant of the coupling condenser 404 and the common resistor 406. Likewise the positive going signal appearing at the grid 397, as the first half of the triode cuts od, is transmitted through the condenser 407 to initiate a cycle in the following stage.

While this circuit is economical to build, the output pulses on the lead 405 are not as great as those produced by the inductively coupled oscillator circuits illustrated in Figures IV or V. This is because of the overlapping or simultaneous transfer of current ow through the cathode resistor 392 whereby a portion of the output voltage from one cathode is lost because of the simultaneous reverse voltage from the other cathode. The dilerence in plate resistor is the principal reason for the usable outpuut voltage `on the cathode connection.

These several circuits illustrating various types of electronically controlled pulse generators all serve the same function of generating a series of pulses of selected number suitable for operating following mutipliers or decades of an electronic counter. In each case the multiplication takes place serially so that there is no danger of simultaneous entery of values into any of the counters and therefore no change of error from such simultaneous entry.

The improved multiplier may also be constructed using a delay line together with suitable amplifiers. Such an arrangement is shown in Figure X. This circuit comprises a tapped delay line 425 having a delay per section of from one =to two microseconds, or more according to requirements. Shaped pulses from an amplifier or other means transmitting start pulses from a key or a previous generator having a time duration less than the time delay of one section are applied to a selector switch 426 having ten points corresponding to the possible values of a digit of the multiplier. The pulses from the switch points are transmitted through diode rectiiiers 427 to taps 423 of the delay line. The number one to number nine switch points are interconnected by rectiiers 429 arranged to pass current from the high valued points to the low valued points. The ends of the delay line are terminated in resistors 430 and 431 to prevent reflections of the voltage pulses from the ends of the line.

The input pulses applied to any selected switch point 222 are transmitted simultaneously to the associated tap of the delay line and to all taps to the right as shown in the ligure. Thus wave trains of n pulses are produced (where n is the number of the tap at which the switch is set) that travel toward the ends of the line 425. As each pulse of the train reaches the right end of the line it drives a grid 432 of an amplier in the positive direction thus producing a negative pulse at a plate 433 of the amplifier. The negative pulses are transmitted directly to a corresponding decade of an electronic counter or to a following generator.

In the multiplier arrangement shown in Figure II a stepping relay was employed to switch the various circuits so as to repetitively employ the multiplier and multiplicand pulse generators. The mechanical speed limitations of a stepping relay limit its operating speed to ap` proximately 60 steps per second which, since the multiplication sequence requires from four to ve steps, results in a total computing time for four digit factors of approximately 1/12 to 1/15 of a second. The operating speed may be materially increased without sacriice of accuracy or reliability and with little increase in complexity of circuits by employing an electronic switching circuit instead of the mechanical stepping relay.

Figures XI and XII show circuits utilizing purely electronic means for switching the circuits involved in operating the multiplier and multiplicand pulse generators sequentially and repetitively. In the circuit shown in Figure XI four ip-ops, i.e. bi-stable multivibrator circuits, one for each factor in the multiplier are arranged to take the place of the stepping relay as far as sequencing the signals are concerned. In this arrangement the ipflops or multivibrators are all normally in their oli condition and are arranged to control gates in the switching circuits so that the entire system is at rest with all of the gates non-conducting. When an initiating or starting impulse is received the irst of the flip-ops is turned to its on condition thereby delivering a voltage impulse through the units selector switch of the multiplier. At the same time this ilip-ilop energizes the gates to connect the multiplicand selector switches shown in Figure II to the corresponding amplifiers and carry storage circuits to register the units partial product in the product counter.

When the pulse has traversed the multiplier puise generator and appears on its output lead it resets to oi all of the flip-ops shown in Figure XI and as these are reset the iirst one transmits a signal to a second to turn it to its on condition thus leaving the second one on and the other three oit This second hip-dop in turn transmits a signal to the tens selector switch of the multiplier at the same time energizing the gates or switching circuits to route the output pulses of the multiplicand generator now representing the tens partial product to the respective amplifiers and decades to add the tens partial product to the amount then in the counter. Upon the completion of the second cycle when the output pulse again appears on the output lead of the multiplier puise generator the flip-Hops are again reset and in the process the third is turned to its on condition thereby transmitting a signal to the hundreds switch of the multiplier setting the gate circuits to route the multiplicand output pulses to the proper counter stages or decades. The same happens again for the fourth flip-lop representing the thousands digit of the multiplier.

If greater capacity is required in the circuit additional ip-iiops are added one for each additional place required.

As shown in Figure XI ip-flops A, B, C, and D each consists of a dual triode tube 440 having a left-hand plate 441, left-hand grid 442, left-hand cathode 443, and cor,- responding right-hand plate 444, grid 445, and cathode 446. The plate 441 is fed from a B+ lead 447 through a plate resistor 44S and is connected to the right-hand grid 445 through a plate to grid resistor 449 which is in parallel with a condenser 450. The grid 445 is tiedvfrto 

